There is a known image processing system that calculates the amounts of correlation between a standard image serving as a standard among a plurality of captured images and the images other than the standard image among the plurality of images and that combines the images other than the standard image at a lower combining ratio as the amount of correlation becomes smaller (see, for example, PTL 1).
If the subject has a fine pattern, a region where the subject is moving (hereinafter simply referred to as “moving region”) is correctly determined to have a larger difference between images, which results in a smaller amount of correlation; however, a region where the subject is stationary (hereinafter simply referred to as “stationary region”) is erroneously determined to have a larger difference between images because of aliasing, which results in a smaller amount of correlation. That is, whereas artifacts due to subject movement and pixel misalignment can be reduced in a moving region, an inaccurate amount of correlation is calculated in a stationary region with aliasing even if the pixels are aligned. This makes it impossible to achieve high resolution.